The present invention relates to a novel resin composition comprising a specific fluorine-containing ethylenic polymer having a functional group and a filler, particularly relates to a resin composition which is prepared by mixing a fluorine-containing ethylenic polymer having a functional group with an inorganic filler or a non-meltable organic filler and has improved mechanical characteristics and sliding property. The resin composition can be used suitably for various applications mentioned hereinbelow.
Further the present invention relates to a molded article which is obtained by heat-treating a molded article prepared from the above-mentioned resin composition and has further improved mechanical characteristics and sliding property. The present invention also relates to a method for producing the molded article.
In general a fluorine-containing resin inherently possesses thermal resistance, chemical resistance and low coefficient of friction, and for purposes to further improve mechanical characteristics and abrasion resistance, trials to add an inorganic or organic filler have been made.
However a fluorine-containing polymer itself has low surface energy and poor dispersibility when mixed with a filler, and the addition of the filler has insufficient effect on mechanical characteristics of the polymer. Also interfacial adhesion between the fluorine-containing polymer and the filler in the mixture is poor. For example, in case of use for a sliding material, the filler in a molded article is easily released from the sliding surface. Thus enough effect on abrasion resistance cannot be obtained and a sliding material having a long life has not been produced.
For the purpose to improve interfacial adhesion between the fluorine-containing resin and the filler, trials to admix a filler which is previously surface-treated with an organic compound have been made.
Various prior arts in which silane compounds are used as a surface-treating agent have been disclosed. For example, a hydrolyzable non-fluorine-containing siloxane compound having terminal amine group is used for surface-treating of glass fiber (U.S. Pat. No. 3,787,281), a silane coupling agent having methyl group bonded with silicon atom is used for surface-treating of a filler (JP-A-7-53780) and a fluorine-containing silane coupling agent such as: 
is used (JP-A-4-272973).
Also there have been disclosed use of a fluorine-containing acid chloride for surface-treating of a glass fiber and carbon fiber (JP-A-4-345691), use of fluoropolyether having, at its molecular end, a functional group such as a siloxane group, alkoxy titanium group, epoxy group or isocyan group for surface-treating of a reinforcing material (JP-B-7-64973), etc.
Since those surface-treating agents basically differ from the fluorine-containing ethylenic polymer which is a matrix component from structural point of view, interfacial adhesion between the fluorine-containing polymer and the filler in the composition prepared by mixing the filler surface-treated by the mentioned methods or in the molded article is not enough, and the addition of such a filler does not have sufficient effect on mechanical characteristics and abrasion resistance of the molded article.
Also many of those surface-treating agents are generally insufficient in thermal resistance and chemical resistance, thus causing foaming and coloring due to decomposition of the surface-treating agent at the time of kneading and molding of the fluorine-containing resin and surface-treated filler. For example, in case of the uses for molded parts, which require thermal durability, among structural materials and sliding materials in the fields of automobiles, industrial machineries, OA apparatuses, domestic electric appliances, etc., there occurs elusion of the surface-treating agent or decomposed product thereof, which lowers initial characteristics (mechanical properties and abrasion resistance).
An object of the present invention is to solve the above-mentioned problems and to provide a resin composition which can give characteristics such as excellent mechanical properties and abrasion resistance to a molded article, while maintaining excellent thermal resistance, chemical resistance, surface characteristics (non-sticking property, low friction property), electrical insulating property and the like of the fluorine-containing polymer. Other objects are to provide a molded article produced from the resin composition and to provide a method for producing the molded article.
The present invention relates to a resin composition comprising:
(A-1) a fluorine-containing ethylenic polymer prepared by copolymerizing at least one of fluorine-containing ethylenic monomers having any one of hydroxyl, carboxyl, a carboxylate salt group, a carboxylate ester group or epoxy in an amount of 0.05 to 30% by mole on the basis of the total amount of monomers, and
(B-1) an inorganic filler or a non-meltable organic filler;
wherein said resin composition comprises 1 to 99.5% by weight of the component (A-1) and 0.5 to 99% by weight of the component (B-1).
It is preferable that the above-mentioned fluorine-containing ethylenic polymer (A-1) is a fluorine-containing ethylenic polymer having a crystalline melting point of not less than 120xc2x0 C.
It is preferable that the above-mentioned fluorine-containing ethylenic polymer (A-1) is a fluorine-containing ethylenic polymer prepared by copolymerization of
(a-1) 0.05 to 30% by mole of at least one of fluorine-containing ethylenic monomers having a functional group and represented by the formula (1): 
wherein Y is xe2x80x94CH2OH, xe2x80x94COOH, a carboxylate salt group, a carboxylate ester group or epoxy, X and X1 are the same or different and each is hydrogen atom or fluorine atom, Rf is a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms, a divalent fluorine-containing oxyalkylene group having 1 to 40 carbon atoms, a divalent fluorine-containing alkylene group having ether bond and 1 to 40 carbon atoms or a divalent fluorine-containing oxyalkylene group having ether bond and 1 to 40 carbon atoms, and
(b-1) 70 to 99.95% by mole of at least one of ethylenic monomers copolymerizable with the component (a-1).
It is preferable that the above-mentioned fluorine-containing ethylenic monomer (a-1) having a functional group is a fluorine-containing monomer represented by the formula (2):
CH2=CFCF2xe2x88x92Rf1xe2x88x92Y1xe2x80x83xe2x80x83(2) 
wherein Y1 is xe2x80x94CH2OH, xe2x80x94COOH, a carboxylate salt group, a carboxylate ester group or epoxy, Rf1 is a divalent fluorine-containing alkylene group having 1 to 39 carbon atoms or xe2x80x94ORf2, in which Rf2 is a divalent fluorine-containing alkylene group having 1 to 39 carbon atoms or a divalent fluorine-containing alkylene group having ether bond and 1 to 39 carbon atoms.
It is preferable that at least one of the above-mentioned ethylenic monomers (b-1) is a fluorine-containing ethylenic monomer.
It is preferable that the above-mentioned fluorine-containing ethylenic monomer (b-1) is tetrafluoroethylene.
It is preferable that the above-mentioned fluorine-containing ethylenic monomer (b-1) is a mixture of 85 to 99.7% by mole of tetrafluoroethylene and 0.3 to 15% by mole of a monomer represented by the formula (3):
CF2=CFxe2x88x92Rf2xe2x80x83xe2x80x83(3) 
wherein Rf2 is xe2x80x94CF3 or ORf3, in which Rf3 is a perfluoroalkyl group having 1 to 5 carbon atoms.
It is preferable that the above-mentioned fluorine-containing ethylenic monomer (b-1) is a mixture of 40 to 80% by mole of tetrafluoroethylene or chlorotrifluoroethylene, 20 to 60% by mole of ethylene and 0 to 15% by mole of other monomer.
It is preferable that the above-mentioned filler (B-1) is a carbon fiber.
It is preferable that the above-mentioned filler (B-1) is a whisker.
It is preferable that the above-mentioned filler (B-1) is a glass filler.
It is preferable that the above-mentioned filler (B-1) is an inorganic filler having cleavage property.
It is preferable that the above-mentioned filler (B-1) is a non-meltable organic fiber.
It is preferable that the above-mentioned filler (B-1) is a carbon fiber.
It is preferable that the above-mentioned filler (B-1) is an aluminium borate whisker.
It is preferable that the above-mentioned filler (B-1) is a glass fiber.
It is preferable that the above-mentioned filler (B-1) is a molybdenum disulfide.
It is preferable that the above-mentioned filler (B-1) is a bronze.
It is preferable that the above-mentioned filler (B-1) is an aramide fiber.
Also the present invention relates to a resin composition comprising:
(A-2) a fluorine-containing ethylenic polymer prepared by copolymerizing at least one of fluorine-containing ethylenic monomers having any one of hydroxyl, carboxyl, a carboxylate salt group, a carboxylate ester group or epoxy in an amount of 0.05 to 30% by mole on the basis of the total amount of monomers,
(B-2) an inorganic filler or a non-meltable organic filler, and
(C) a fluorine-containing ethylenic polymer having no functional group in its branched chain,
wherein an amount of the component (A-2) is from 1 to 50% by weight, an amount of the component (B-2) is from 0.5 to 8 0% by weight and an amount of the component (C) is the residual amount, provided that the sum of (A-2) and (C) is from 20 to 99.5% by weight and (C)/((A-2)+(C))xe2x89xa70.4.
It is preferable that the above-mentioned fluorine-containing ethylenic polymer (C) having no functional group in its branched chain is a fluorine-containing ethylenic polymer having a crystalline melting point of not less than 120xc2x0 C.
It is preferable that the above-mentioned fluorine-containing ethylenic polymer (C) having no functional group in its branched chain is polytetrafluoroethylene, tetrafluoroethylene-perfluoro(alkyl vinyl ether) copolymer, tetrafluoroethylene-hexafluoropropylene copolymer or ethylene-tetrafluoroethylene copolymer.
Also the present invention relates to a molded article produced by molding a resin composition comprising:
(A-3) a fluorine-containing ethylenic polymer which is prepared by copolymerizing at least one of fluorine-containing ethylenic monomers having any one of hydroxyl, carboxyl, a carboxylate salt group, a carboxylate ester group or epoxy in an amount of 0.05 to 30% by mole on the basis of the total amount of monomers and has a crystalline melting point of not less than 120xc2x0 C., and
(B-3) an inorganic filler or a non-meltable organic filler,
wherein said resin composition comprises 1 to 99.5% by weight of the component (A-3) and 0.5 to 99% by weight of the component (B-3),
and then heat-treating the obtained molded article at a temperature of not less than 100xc2x0 C. and not more than the crystalline melting point of the fluorine-containing ethylenic polymer (A-3).
It is preferable that the above-mentioned fluorine-containing ethylenic polymer (A-3) is a fluorine-containing ethylenic polymer prepared by copolymerization of
(a-2) 0.05 to 30% by mole of at least one of fluorine-containing ethylenic monomers having a functional group and represented by the formula (1): 
wherein Y is xe2x80x94CH2OH, xe2x80x94COOH, a carboxylate salt group, a carboxylate ester group or epoxy, X and X1 are the same or different and each is hydrogen atom or fluorine atom, Rf is a divalent fluorine-containing alkylene group having 1 to 40 carbon atoms, a divalent fluorine-containing oxyalkylene group having 1 to 40 carbon atoms, a divalent fluorine-containing alkylene group having ether bond and 1 to 40 carbon atoms or a divalent fluorine-containing oxyalkylene group having ether bond and 1 to 40 carbon atoms, and
(b-2) 70 to 99.95% by mole of at least one of ethylenic monomers copolymerizable with the component (a-2).
It is preferable that at least one of the above-mentioned ethylenic monomers (b-2) is a fluorine-containing ethylenic monomer.
It is preferable that the above-mentioned fluorine-containing ethylenic monomer (b-2) is tetrafluoroethylene.
It is preferable that the above-mentioned fluorine-containing ethylenic monomer (b-2) is a mixture of 85 to 99.7% by mole of tetrafluoroethylene and 0.3 to 15% by mole of a monomer represented by the formula (3):
CF2=CFxe2x88x92Rf2xe2x80x83xe2x80x83(3) 
wherein Rf2 is xe2x80x94CF3 or ORf3, in which Rf3 is a perfluoroalkyl group having 1 to 5 carbon atoms.
It is preferable that the above-mentioned fluorine-containing ethylenic monomer (b-2) is a mixture of 40 to 80% by mole of tetrafluoroethylene, 20 to 60% by mole of ethylene and 0 to 15% by mole of other monomer.
It is preferable that the above-mentioned filler (B-3) is a carbon fiber.
It is preferable that the above-mentioned filler (B-3) is a whisker.
It is preferable that the above-mentioned filler (B-3) is an aluminium borate whisker.
It is preferable that the above-mentioned filler (B-3) is a glass filler.
It is preferable that the above-mentioned filler (B-3) is an inorganic filler having cleavage property.
It is preferable that the above-mentioned filler (B-3) is a non-meltable organic fiber.
Further the present invention relates to a method for producing the above-mentioned molded article, characterized in that a molded article obtained by molding the above-mentioned resin composition is heat-treated at a temperature of not less than 100xc2x0 C. and not more than a crystalline melting point of the fluorine-containing ethylenic polymer (A-1).
It is preferable that a molded article obtained by molding the above-mentioned resin composition is heat-treated at a temperature of not less than 200xc2x0 C. and not more than the crystalline melting point of the fluorine-containing ethylenic polymer (A-1).
It is preferable that a molded article obtained by melting and molding the above-mentioned resin composition is heat-treated at a temperature of not less than 200xc2x0 C. and not more than the crystalline melting point of the fluorine-containing ethylenic polymer (A-1).